Improvement in grinding saws



v rollers.

UNITED STATES PATEANl OFFICE.

JOHN G. BAKER, OF WASHINGTON, DISTRICT OF COLUMBIA.

IMPROVEMENT IN GRINDING- SAWS.

Specification forming part of Letters Patent No. 4 1,4 I 9, dated February 2, 1864; antedated January 22, 1864.

o all whom, t may concern,.-

Be it known that I, JOHN G. BAKER, of Washington city, in the District of Columbia, have invented certain new and useful Improvements in Machines for Grinding and Polishing Saws; and I do hereby declare that the following is a full and exact description thereof, lreference being had to the accompanying drawings, and to the letters of reference thereon marked.

In the several figures similar characters refer to like parts.

Figure l is a side elevation. Fig. 2 is a plan View. Fig. 3 is an end elevation. Fig. 4 is a longitudinal vertical section of the feeding-frame, showing the operation of the feed- Fig. 5 shows the slotted traverse-bar.

The caps which cover the grit-stones are not seen in the drawings7 being detached in order to represent other parts of the machine more clearly.

The nature ofmy invention consists in grind` ing saws thinner at the back than at the edge between two grindstones set at angle to each other, which simultaneously traverse the faces of the saw, thereby giving the saw-blade the desired wedge shape and grinding both sides at once; also, in continuously feeding the sawblades down through the feed-frame between the feed-rollers and between the stones; also, in making the casing (which contains the water used in grinding, and which covers the stone and prevents the iiying of the water) traverse simultaneously with the stones.

To enable others to make and use my invention, I will describe its construction and operation.

In the drawings, A indicates a stout rectangular frame-work of a height from the iioor somewhat more than the radius of the grindstones. Along the edges of the top of the frame are laid grooved Ways a, upon which the four plumber-blocks, B, slide.

C are the grinding or polishing stones, which may be of any suitable substance or size. Each of the stones C is provided with an axle, D, whose bearings arevin the sliding plumberblocks D. These axles D extend beyond their journals sufficiently for the attachment of the devices which give them both a revolving and a traverse lateral motion.

E are four right and left screws, which lie in the grooves of ways a and operate the plumber-blocks so as to make the stones approach each other at the vdesired angle at which they are. set in the first instance.

F is the slotted traverse-bar. In the slots of this bar the necks-b (see Fig. 2) of the axles D are secured by collars c. The ends of the bar F are pivoted like a connecting-rod to the arms d of the extension-cranks G.

Gare extension-cranks upon the upper ends of the vertical shafts H, whose bracket journal-boxes extend from the frame-work. The throw or swing of the cranks is regulated by the set-screws e, which regulate the .distance of the crank-pins d from the main crank-shafts H.

I is a vertical double rectangular frame secured to the frame A, and is so constructed (see Fig. 4) as to be between the two stones except at arshort central space, where the curved faces of the stones (red lines, Fig. 4) pass through and touch each other, or the opposite sides of a saw. The two halves of this are secured together by means of the serew-boltsf, which are provided with rubber springs g.

J J are two pairs of feed-rollers, having their bearings in the opposite halves of the frame I. The springs g serve to make the feed-rollers approach each other so as to come into close Contact with the saw and feed it down between the two stones.

K is the seat for the operative, who feeds the saws into the slit z' of frame I, pushing them downward until they are taken hold of by the feed-rollers.

L is the operating-wheel (on the upper part of the wheel at the left of the seat) for controlling the stones and making them approach or retire from each other, as may be needed in the different stages of the grinding or polishing process.

A suitable system of endless chains M and chain-pulleys N connect the wheel L to the four right and left screws E, so that turningwheel L turns the screws E so as to operate the stones.

An endless chain,.O, and chain-pulleys on the lower ends of vertical shafts H make the expansion-cranks G move alike.

' frame A. The casin g traverses with the stones.

T are the casing-caps, shown in drawings only by dotted lines in Fig. 1.

It is well known that a good hand-saw should be ground thinner on the back than on the cutting-edge, tapering regularly from the edge to the back. Unless the saw is thus ground it will be necessary to give a large degree of set to its teeth in order that it may cut freely without buckling.77 When properly ground, however, there is no need of any set. The mode in common use with the best sawmakers for grinding their saws with ataper is to fasten the saw-blade to a board, which a skilled workman holds on his knee against a grindstone, shifting the saw from toe to heel until it is finished. It is evident that this 'method is slow, expensive, and imperfect.

Many devices have been designed for this purpose, but none have proven satisfactory.

A first-rate hand-saw should be about four f one-hundredths ofan inch thick on the cuttingedge and three one-hundredths, of an inch on the back.

In the building of my machine the plumberblocks are cast hollow and iitted to their ways,

the right and left screws, endless chains, pulsleys, and wheel L being so arranged asto operate the plumber-blocks squarely and simultaneously. The axles are then put into the hollows of the plumber-blocks, and Babbitt metal is run around them. By this arrangementthe stones are kept constantly at the desired angle, and as they wear away by use they can y contrivance for forcing the saw down between them, counteracting their tendency to keep it stationary. This is accomplished by my frame I, which contains the feed-rollers andguidcs the saws. At the same time that the saw is' descending the two stones are grinding it upon both sides, giving it the desired taper, and at the same time the two stones are traversing back and forth across the faces of thesaw, the traversing being eected by the action of the expansion-cranks upon the slotted traversebar which is connected to and operates the axles of the stones. Fig. Xis a diagram showing the operation of the stones,which are here shown at an exaggerated angle; o, the saw. The red and dotted lines indicate the opposite eX- tremes of the traverse motion. Vhen the stones first commence grinding the saw, their edges ll iirst come in contact with the saw at its edges 2 2, so that if there was no traversing across the saw the stones themselves 'would soon be worn away at a bevel, so that succeeding saws would, be ground straight; but this disadvantage is entirely overcome by the traversing of the entire faces of-both stones past the edges 2 2 of the saw, so that the faces of the stones are kept straight so as to retain their initial relative angle.l After a suitable number of saws have gone through the machine the operative gives the wheel L a veryslight turn, so as to bring the stones somewhat nearer together. The saws are then run through again, andhave another angular portion ground oii'. This process is repeated a suflicient num- -ber of times until the grinding is inished and the saws are ready for polishing.

Fig. Z is a magniiied View of a saw with exaggerated taper, the red lines indicating the successive angular portions ground off at the several passages of the saw through' the machine.

Having thus fully described the construction and operation of my invention,what I claim as new, and desire to secure by Letters Patent, isj l. Grinding saws by means of two traversing grindstones set atan angle with each other.

JOHN G. BAKER.

Witnesses:

D. M. MnFFoRD, W. G. CLAYTON. 

